1. Field of the Invention
The present invention relates to a printing apparatus, and more particularly to a printing apparatus with several interchangeable printing heads for obtaining desired typefont.
2. Description of the Prior Art
In the printing apparatus, for example serial thermal printers, the displacement of the carriage having a thermal printing head has generally been achieved by a stepping motor because of simplicity in drive circuit and ease in control for performing reciprocating motion. However such a drive system has been associated with a drawback that the moving pitch of the carriage has to be constant because of the constant rotating angle of the stepping motor, eliminating the possibility of employing plural typefonts different in size and shape for the characters.
In order to avoid said drawback, the present applicant has disclosed, in its Japanese patent application No. 116845/1980, a printing apparatus capable of automatically regulating the printing pitch according to the typefont of the printing head. In said printing apparatus, however, the user has not necessarily been assuring whether the printing is achieved with the desired typefont.